10-GHz Optical Comb in L-Band Region With Brillouin/Erbium-Doped Fibre Laser

A multiwavelength Brillouin/erbium fibre laser (BEFL) which operates in the long wavelength (L-band) region is demonstrated for potential applications in an L-band wavelength division multiplexing (WDM) communication system. The laser configuration consists of a long erbium-doped fibre to enable L-band amplification where two 3-dB couplers take a portion of the generated BEFL signal and re-inject it into the single mode fibre to seed a cascaded BEFL line in the same direction as the first BEFL line. A stable and strong laser comb of up to five lines with 10-GHz spacing has been obtained with a Brillouin pump (BP) of 9.2 mW and a 980 nm pump of 92 mW. The BEFL has shown a broad tuning range with a tuning characteristic for line #1 which is flat over a range greater than 9.9 nm.     

Coordination of solvent molecules to VO(acac)<Subscript>2</Subscript> complexes in solution studied by hyperfine sublevel correlation spectroscopy and pulsed electron nuclear double resonance

Interactions and binding sites of the solvent molecules chloroform and ethanol to bis(acetylacetonate)oxovanadium(IV) (VO(acac)₂) complexes in (frozen) solutions have been investigated by pulsed electron nuclear double resonance, sum peak electron spin echo envelope modulation and hyperfine sublevel correlation spectroscopy. The experimental proton hyperfine coupling data of coordinating solvent molecules have been interpreted using quantum chemical calculations (density functional theory). Experimental and computed hyperfine couplings indicate that ethanol coordinates to vanadium in the equatorial plane of VO(acac)₂ and chloroform interacts via hydrogen bonding to oxygens of the acac ligands.     

Phytofabrication of silver nanoparticles from Limonia acidissima leaf extract and their antimicrobial,antioxidant and its anticancer prophecy

Green synthesis of nanoparticles by eco-friendly methods is a recent technique which draws the attention of researchers because of the reward over many conventional chemical methods. The present work focuses on aqueous Limonia acidissima leaf extract in synthesizing silver nanoparticles and its applications in a simple way. The silver nanoparticles formed were characterized by Infrared, Ultra violet-visible, X-ray diffraction, transmission electron microscopic, and atomic force microscopic techniques. The powder X-ray diffraction studies and transmission electron microscopic images reveal that the silver nanoparticles synthesized were approximately 10–40 nm and have a spherical structure. The nanoparticles were assayed for their antibacterial, antifungal and antioxidant activity. The antimicrobial studies for the silver nanoparticles show a maximum zone of inhibition of 8.8 mm for Bacillus subtilis bacteria and 8.5 mm for Candida albicans fungi at 3 and 1 μg/mL respectively. In-silico ADMET studies reveal that the toxicity, bioactivity, pharmacokinetics and drug-likeness properties of Limonia acidissima leaf extract is good. The molecular docking studies show that the microbial activity is high for Bacillus subtilis and Candida albicans showing the coincidence of the in silico and in vitro studies as expected. The free radical scavenging activity of nanoparticles is 80 for 100 μg/mL. The 50% of inhibition of silver nanoparticles against human breast cancer cell lines is 18 μg/mL. It is evident that silver nanoparticles would be helpful in treating cancer cell lines and have great perspectives in the biomedical sector.     

Inhibitive properties of a phosphonate-based formulation for corrosion control of carbon steel

The aim of the present work was to study the corrosion inhibition of carbon steel using a ternary formulation. This new ternary inhibitor formulation, viz., 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), with zinc ions and silicate ions was used to protect carbon steel from corrosion in a low-chloride environment. The gravimetric studies showed that 96 % inhibition efficiency was achieved with the ternary system consisting of 50 ppm PBTC, 50 ppm Zn²⁺ ions, and 10 ppm silicate ions. Out of 0.310 mmol of Zn²⁺ ions, 0.218 mmol was diffused from the bulk of the solution to the metal surface, as revealed from the studies of the solutions by atomic absorption spectroscopy (AAS). Electrochemical methods (potentiostatic polarization and electrochemical impedance spectroscopy) and surface characterization techniques [Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and atomic force microscopy (AFM)] were used to ascertain the nature of the protective film and for explaining the mechanistic aspects of corrosion inhibition.     

18‐Crown‐6 Catalyzed Microwave‐mediated Synthesis of Symmetric Bis‐Heterocyclic Compounds under Solvent‐free Condition

An efficient, solvent‐free and 18‐crown‐6 catalyzed method for the synthesis of N‐alkyl‐4‐(4‐(5‐(2‐(alkyl‐amino)thiazol‐4‐yl)pyridin‐3‐yl)phenyl)thiazol‐2‐amine, N‐alkyl‐4‐(5‐(2‐alkyamino)thiazol‐4‐yl)pyridine‐3‐yl)thiazol‐2‐amine, and 4,4′‐bis‐{2‐[amino]‐4‐thiazolyl}biphenyl bis‐heterocyclic derivatives via microwave accelerated cyclization is presented.     

Influence of barium titanate nanofiller on PEO/PVdF-HFP blend-based polymer electrolyte membrane for Li-battery applications

Organic-inorganic hybrid membranes based on poly(ethylene oxide) (PEO) 6.25 wt%/poly(vinylidene fluoride hexa fluoro propylene) [P(VdF-HFP)] 18.75 wt% were prepared by using various concentration of nanosized barium titanate (BaTiO₃) filler. Structural characterizations were made by X-ray diffraction and Fourier transform infrared spectroscopy, which indicate the inclusion of BaTiO₃ in to the polymer matrix. Addition of filler creates an effective route of polymer-filler interface and promotes the ionic conductivity of the membranes. From the ionic conductivity results, 6 wt% of BaTiO₃-incorporated composite polymer electrolyte (CPE) showed the highest ionic conductivity (6 × 10^?3 Scm^?1 at room temperature). It is found that the filler content above 6 wt% rendered the membranes less conducting. Morphological images reveal that the ceramic filler was embedded over the membrane. Thermogravimetric and differential thermal analysis (TG-DTA) of the CPE sample with 6 wt% of the BaTiO₃ shows high thermal stability. Electrochemical performance of the composite polymer electrolyte was studied in LiFePO₄/CPE/Li coin cell. Charge-discharge cycle has been performed for the film exhibiting higher conductivity. These properties of the nanocomposite electrolyte are suitable for Li-batteries.     

Spectroscopic characterization of indian standard sand

The characterization of Indian standard sand (IS650:1991 as per B.I.S. approval) was performed by X-ray diffraction, IR and Raman spectroscopy, and nuclear magnetic resonance techniques. The principal reflections occurring at the d-spacings of 4.2408, 3.3440, and 1.8292 ? confirm the presence of α-quartz crystalline structure in the sample. The calculated unit cell parameters are: a = 4.9294 ?, c = 5.4093 ?, and V = 113.832 ?³. Mid-IR spectrum shows the characteristic doublet for α-quartz at 797 and 778 cm^–1. The Al/Al+Si ratio has been calculated from the position of the absorption band at 1100 cm^–1. Raman spectrum of the sample has two strong peaks at 203 cm^–1 and at 462 cm^–1 for A1 vibrational mode characteristic of α-quartz. Two bands at 1410 and 1930 nm in near-IR spectrum indicate the presence of both molecular water and an OH group. A broad double band centered near 1210 nm and a weak band at 1050 nm attest the presence of Fe²⁺ and Fe³⁺ respectively in the sample. The signal near g ∼ 4 is characteristic of isolated Fe³⁺ ions in the distorted octahedral or tetrahedral crystalline field. ²⁹Si NMR spectrum shows a strong signal at –107 ppm corresponding to quartz.     

Nonlinear vibrations and damping of fractional viscoelastic rectangular plates

Nonlinear Dynamics - A new model-free robust control scheme for payload swing angle attenuation of two-dimensional crane systems with varying rope length is introduced in this work. The proposed...